Method for scheduling vehicle-to-vehicle communications

Abstract

A system, communication device, and method for scheduling transmissions from the communication device. The device predicts an arrival time of a next packet for transmission when a current packet arrives in a transmission buffer. The device plans a future transmission time of the next packet based on the predicted arrival time of the next packet, and books transmission resources for the planned future transmission time. If the next packet has arrived a Tdrop time period before the planned future transmission time, the device transmits the next packet. If the next packet has not arrived at that time, the device re-plans the future transmission time of the next packet. The device may then unbook the transmission resources for the planned future transmission time, book transmission resources for the re-planned future transmission time, and notify other communication devices that the unbooked transmission resources are available for use by the other communication devices.

What is claimed is: 
     
       1. A method of scheduling transmissions from a communication device, the method comprising:
 predicting an arrival time of a next packet for transmission when or after a current packet arrives; 
 planning a future transmission time of the next packet based on the predicted arrival time of the next packet; and 
 booking transmission resources for the planned future transmission time of the next packet. 
 
     
     
       2. The method according to  claim 1 , wherein predicting includes predicting the arrival time of the next packet for transmission based on arrival times of N most recently received packets. 
     
     
       3. The method according to  claim 1 , wherein planning a future transmission time of the next packet includes utilizing a planning method selected from a group consisting of:
 computing the future transmission time as a function of the predicted arrival time of the next packet alone; 
 computing the future transmission time as a function of the predicted arrival time of the next packet plus a parameter providing a minimum time between the arrival time of the next packet and the actual transmission of the next packet; 
 computing the future transmission time as a function of the predicted arrival time of the next packet and the current time; and 
 computing the future transmission time as a function of the predicted arrival time of the next packet and the transmission time of the current packet. 
 
     
     
       4. The method according to  claim 1 , further comprising:
 determining whether the next packet has arrived before the planned future transmission time of the next packet; and 
 transmitting the next packet in response to determining that the next packet has arrived before the planned future transmission time of the next packet. 
 
     
     
       5. The method according to  claim 4 , further comprising:
 re-planning the future transmission time of the next packet in response to determining that the next packet has not arrived before the planned future transmission time of the next packet. 
 
     
     
       6. The method according to  claim 1 , further comprising:
 determining whether the next packet has arrived before a defined time period (Tdrop) prior to the planned future transmission time; and 
 transmitting the next packet in response to determining that the next packet has arrived before the Tdrop time period prior to the planned future transmission time of the next packet. 
 
     
     
       7. The method according to  claim 6 , further comprising, in response to determining that the next packet has not arrived before the Tdrop time period prior to the planned future transmission time of the next packet:
 re-planning the future transmission time of the next packet; 
 unbooking the transmission resources for the planned future transmission time of the next packet; and 
 booking transmission resources for the re-planned future transmission time of the next packet. 
 
     
     
       8. The method according to  claim 7 , further comprising notifying other communication devices that the unbooked transmission resources are available for use by the other communication devices. 
     
     
       9. The method according to  claim 8 , wherein notifying includes sending a control information packet at least the Tdrop time period before the planned future transmission time, the control information packet including:
 an indicator for booking transmission resources for the re-planned future transmission time of the next packet; 
 an indicator for informing the other communication devices that the communication device will not use the booked transmission resources for the planned future transmission time of the next packet; and 
 a value indicating the planned future transmission time of the unbooked transmission resources. 
 
     
     
       10. The method according to  claim 1 , wherein the communication device is a wireless communication device. 
     
     
       11. A communication device, comprising:
 a processor; 
 a non-transitory memory for storing instructions executable by the processor; 
 a transmit buffer connected to the processor; and 
 an interface connected to the processor for transmitting packets from the communication device; 
 wherein, when or after a current packet arrives in the transmit buffer, the processor is configured to execute the instructions in the memory, thereby causing the processor to:
 predict an arrival time of a next packet for transmission; 
 plan a future transmission time of the next packet based on the predicted arrival time of the next packet; and 
 book transmission resources for the planned future transmission time of the next packet. 
 
 
     
     
       12. The communication device according to  claim 11 , wherein the processor is configured to predict the arrival time of the next packet for transmission based on arrival times of N most recently received packets. 
     
     
       13. The communication device according to  claim 11 , wherein the processor is configured to plan a future transmission time of the next packet utilizing a planning method selected from a group consisting of:
 computing the future transmission time as a function of the predicted arrival time of the next packet alone; 
 computing the future transmission time as a function of the predicted arrival time of the next packet plus a parameter providing a minimum time between the arrival time of the next packet and the actual transmission of the next packet; 
 computing the future transmission time as a function of the predicted arrival time of the next packet and the current time; and 
 computing the future transmission time as a function of the predicted arrival time of the next packet and the transmission time of the current packet. 
 
     
     
       14. The communication device according to  claim 11 , wherein the processor is further configured to:
 determine whether the next packet has arrived before a defined time period (Tdrop) prior to the planned future transmission time; and 
 transmit the next packet in response to determining that the next packet has arrived before the Tdrop time period prior to the planned future transmission time of the next packet. 
 
     
     
       15. The communication device according to  claim 14 , wherein, in response to determining that the next packet has not arrived before the Tdrop time period prior to the planned future transmission time of the next packet, the processor is further configured to:
 re-plan the future transmission time of the next packet; 
 unbook the transmission resources for the planned future transmission time of the next packet; and 
 book transmission resources for the re-planned future transmission time of the next packet. 
 
     
     
       16. The communication device according to  claim 15 , wherein the processor is further configured to notify other communication devices that the unbooked transmission resources are available for use by the other communication devices. 
     
     
       17. The communication device according to  claim 16 , wherein the processor is configured to notify the other communication devices by sending a control information packet at least the Tdrop time period before the planned future transmission time, the control information packet including:
 an indicator for booking transmission resources for the re-planned future transmission time of the next packet; 
 an indicator for informing the other communication devices that the communication device will not use the booked transmission resources for the planned future transmission time of the next packet; and 
 a value indicating the planned future transmission time of the unbooked transmission resources. 
 
     
     
       18. The communication device according to  claim 11 , wherein the communication device is a wireless communication device. 
     
     
       19. A system for scheduling transmissions from a plurality of communication devices involved in a communication using a shared medium, the system comprising:
 within each of the plurality of communication devices, an apparatus comprising:
 a processor; 
 a non-transitory memory for storing instructions executable by the processor and for buffering packets to be transmitted; and 
 an interface connected to the processor for transmitting packets from the communication device; 
 
 wherein, when or after a current packet arrives in the memory, the processor is configured to execute the instructions in the memory, thereby causing the processor to:
 predict an arrival time of a next packet for transmission; 
 plan a future transmission time of the next packet based on the predicted arrival time of the next packet; 
 book transmission resources for the planned future transmission time of the next packet; and 
 notify other communication devices of the booked transmission resources. 
 
 
     
     
       20. The system according to  claim 19 , wherein the processor within each of the plurality of communication devices is further configured to predict the arrival time of the next packet for transmission based on arrival times of N most recently received packets. 
     
     
       21. The system according to  claim 19 , wherein the processor within each of the plurality of communication devices is further configured to plan a future transmission time of the next packet utilizing a planning method selected from a group consisting of:
 computing the future transmission time as a function of the predicted arrival time of the next packet alone; 
 computing the future transmission time as a function of the predicted arrival time of the next packet plus a parameter providing a minimum time between the arrival time of the next packet and the actual transmission of the next packet; 
 computing the future transmission time as a function of the predicted arrival time of the next packet and the current time; and 
 computing the future transmission time as a function of the predicted arrival time of the next packet and the transmission time of the current packet. 
 
     
     
       22. The system according to  claim 19 , wherein the processor within each of the other communication devices is further configured to avoid transmitting at the planned future transmission time. 
     
     
       23. The system according to  claim 19 , wherein the processor within each of the plurality of communication devices is further configured to:
 determine whether the next packet has arrived before a defined time period (Tdrop) prior to the planned future transmission time; and 
 transmit the next packet in response to determining that the next packet has arrived before the Tdrop time period prior to the planned future transmission time of the next packet. 
 
     
     
       24. The system according to  claim 23 , wherein, in response to determining that the next packet has not arrived before the Tdrop time period prior to the planned future transmission time of the next packet, the processor within each of the plurality of communication devices is further configured to:
 re-plan the future transmission time of the next packet; 
 unbook the transmission resources for the planned future transmission time of the next packet; and 
 book transmission resources for the re-planned future transmission time of the next packet. 
 
     
     
       25. The system according to  claim 24 , wherein the processor within each of the plurality of communication devices is further configured to notify the other communication devices that the unbooked transmission resources are available for use by the other communication devices. 
     
     
       26. The system according to  claim 25 , wherein the processor within each of the plurality of communication devices is configured to notify the other communication devices by sending a control information packet at least the Tdrop time period before the planned future transmission time, the control information packet including:
 an indicator for booking transmission resources for the re-planned future transmission time of the next packet; 
 an indicator for informing the other communication devices that the communication device will not use the booked transmission resources for the planned future transmission time of the next packet; and 
 a value indicating the planned future transmission time of the unbooked transmission resources. 
 
     
     
       27. The system according to  claim 19 , wherein the plurality of communication devices are wireless communication devices. 
     
     
       28. A method of scheduling transmissions from a communication device of a group of communication devices involved in common communication sharing a medium and where transmission scheduling is distributed among the group members, the method comprising:
 predicting an arrival time of a next packet for transmission in a transmit buffer when or after a current packet arrives; 
 planning a future transmission time of the next packet based on the predicted arrival time of the next packet; 
 booking transmission resources for the planned future transmission time of the next packet; 
 notifying other communication devices of the group of communication devices of the planned future transmission time; 
 determining whether the next packet has arrived before the planned future transmission time of the next packet; 
 transmitting the next packet in response to determining that the next packet has arrived before the planned future transmission time of the next packet; and, 
 unbooking the transmission resources for the planned future transmission time of the next packet in response to determining that the next packet has not arrived before the planned future transmission time of the next packet. 
 
     
     
       29. The method of  claim 28 , further comprising:
 notifying other communication devices that the unbooked transmission resources are available for use by the other communication devices. 
 
     
     
       30. A communication device of a group of communication devices involved in common communication sharing a medium and where transmission scheduling is distributed among the group members, the communication device comprising:
 a processor; 
 a non-transitory memory for storing instructions executable by the processor; 
 a transmit buffer connected to the processor; and 
 an interface connected to the processor for transmitting packets from the communication device; 
 the processor is configured to execute the instructions in the memory, thereby causing the processor when or after a current packet arrives in the transmit buffer to:
 predict an arrival time of a next packet for transmission in said transmit buffer; 
 plan a future transmission time of the next packet based on the predicted arrival time of the next packet; 
 book transmission resources for the planned future transmission time of the next packet; 
 notify other communication devices of the group of communication devices of the planned future transmission time; 
 determine whether the next packet has arrived before the planned future transmission time of the next packet; 
 transmit the next packet in response to determining that the next packet has arrived before the planned future transmission time of the next packet; and, 
 unbook the transmission resources for the planned future transmission time of the next packet. 
 
 
     
     
       31. The communication device of  claim 30 , wherein the processor is further configured to:
 notify the other communication devices that the unbooked transmission resources are available for use by the other communication devices. 
 
     
     
       32. A system for scheduling transmissions from a plurality of communication devices involved in a communication using a shared medium and where transmission scheduling is distributed among the plurality of communication devices, the system comprising:
 within each of the plurality of communication devices, an apparatus comprising:
 a processor; 
 a storage unit for storing instructions executable by the processor and for buffering packets to be transmitted; and 
 an interface connected to the processor for transmitting packets from the communication device; 
 the processor is configured to execute the instructions in the storage unit, thereby causing the processor when or after a current packet arrives in the storage unit to: 
 
 predict an arrival time of a next packet for transmission in said storage unit; 
 plan a future transmission time of the next packet based on the predicted arrival time of the next packet; 
 book transmission resources for the planned future transmission time of the next packet; 
 notify other communication devices of the plurality of communication devices of the planned future transmission time; 
 determine whether the next packet has arrived before the planned future transmission time of the next packet; 
 transmit the next packet in response to determining that the next packet has arrived before the planned future transmission time of the next packet; and, 
 unbook the transmission resources for the planned future transmission time of the next packet in response to determining that the next packet has not arrived before the planned future transmission time of the next packet. 
 
     
     
       33. The system of  claim 32 , wherein the processor is further configured to:
 notify the other communication devices that the unbooked transmission resources are available for use by the other communication devices.